The present invention relates to the synthesis of ethanol from biomass and, more particularly to such synthesis by a catalytic thermochemical process.
Conversion of biomass to ethanol by fermentation techniques is a well practiced process, especially with the emerging importance of gasohol in today's economy. Conventional fermentation techniques, however, suffer from a number of drawbacks including, for example, protracted reaction times, the need for sterile reaction conditions, the need for purified feedstocks, the production of voluminous by-products, and an energy intensive distillation operation for recovery of ethanol from water. The need for an alternate route for converting biomass to ethanol thus exists. Unfortunately, no alternative process has emerged in the marketplace.
In studying the reaction mechanisms involved in fermentation of sugar, it has been reported that an aqueous solution of some sugars can be converted to lactic acid in the presence of an alkali metal or alkaline earth metal hydroxide or oxide. Montgomery and Ronca, "Chemical Production" of Lactic and Other Acids from Molasses", Industrial and Engineering Chemistry, Vol. 45, No. 5, pp 1136-1147 (1953) and references cited therein. In other unrelated research, it has been reported that certain alkali metal or alkaline earth metal lactate salts could be decarboxylated to produce a mixture of several organic liquids and gases and on occasion some ethanol. Hanriot, "Sur la decomposition pyrogenee des acides de la serie grasse", Nouv. Ser. T. XLV, Societe Chimique, pp 79-81 (1886); Buchner and Meisenheimer, "Die chemischen Vorgange bei der alkoholischen Gahrung" Berk. deut. chem. Ges., 38, 620-630 (1905) and Fischer, Schrader and Wolter, "Uber die Entkarboxylierung der Milschaure, Gesamm. Abh. Kenntnis Kohle, 6, 99-107 (1923). For further studies on lactic acid as it may relate to fermentation of sugars, reference is made to the text by C. H. Holten, Lactic Acid: Properties in Chemistry of Lactic Acid and Derivatives, Verlag Chemie, GmbH, Copenhagen, Denmark.
The present invention has solved the long standing problem of converting biomass into ethanol by a process which does not involve fermentation. Also, substantially all of the disadvantages inherent in conventional fermentation of biomass are obviated by the present invention.